Technical Field
The disclosure concerns a method of forming layered structures having conductive Cobalt interconnects for interlayer connectivity in an integrated circuit such as a complementary metal oxide semiconductor (CMOS) structure.
Background Discussion
As critical dimension (CD) is reduced for CMOS devices, line resistance of the conductive interconnects increases. The conductive interconnects are typically Copper. In order to address the problem of increasing line resistance, the conductive interconnects may be formed of Cobalt instead of Copper.
Following chemical mechanical polishing (CMP), exposed surfaces of the Cobalt interconnects tend to form an overlying thin Cobalt oxide layer, which must be removed. One method for removing the thin Cobalt oxide layer is to treat the structure with an ammonia plasma (a plasma formed of NH3). This treatment can enhance time dependent dielectric breakdown (TDDB) behavior of the structure. It is a challenge for one to remove the Cobalt oxide layer without damaging the under layer.